1. Field of the Invention
The present invention concerns a device and a process for lining a bifurcation in a well, particularly in an oil well.
2. Description of Related Art
The invention finds a particular application in sealing and lining the area where a main bore that is generally (although not necessarily) vertical joins an oblique bore running from the vertical bore, known in the art as a "side track".
This type of secondary bore is used to access lateral oil-bearing reservoirs when the main reservoir is exhausted or has become uneconomic or simply to increase the productivity of the well.
This type of bore also enables the production area to be significantly expanded into areas where access is difficult without having to drill a new well from the surface; this applies in particular to production from deposits under the sea.
Prior art processes use metal tubes to consolidate and seal the borehole, both for the main well and often for the secondary wells, and it is difficult to obtain a good seal in the area of the join.
It has already been proposed to line a well by means of an initially flexible radially deformable tubular preform that can be expanded by internal pressure and hardened in situ by heating its wall to polymerize it.
This technique is described in documents WO-94/21887 and WO-94/25655 and in unpublished French patent application 94 08691 of Jul. 7 1994, for example.
The present invention proposes to transpose this technique known in itself to lining the bifurcation area in which the main bore and the secondary bore join.